Logarithmic profile mapping and Retinex edge preserving for restoration of low illumination images
N. M. Kwok, Haiyan Shi, Gu Fang, Ching-Feng Lin, Chin Yeow Wong, San Chi Liu, Shilong Liu, Md Arifur Rahman · 2016
Contents carried in an image are valuable information sources for many scientific and engineering applications. However, if the image is captured under low illumination conditions a large portion of the image appears dark and this heavily degrades the image quality. In order to solve this problem, a restoration algorithm is developed here that transforms the low input brightness to a higher value using a logarithmic mapping function. The mapping is further refined by a linear weighting with the input to reduce the un-necessary amplification at regions with high brightness. Moreover, fine details in the image are preserved by applying the Retinex principle to extract and then re-insert object edges. Results from experiments using low and normal illumination images have shown satisfactory performances with regard to the improvement in information contents and the mitigation of viewing artifacts.